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  <h1 class="refname">PDO::prepare</h1>
  <p class="verinfo">(PHP 5 &gt;= 5.1.0, PECL pdo &gt;= 0.1.0)</p><p class="refpurpose"><span class="refname">PDO::prepare</span> &mdash; <span class="dc-title">
   Prepares a statement for execution and returns a statement object
  </span></p>

 </div>
 <div class="refsect1 description" id="refsect1-pdo.prepare-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="modifier">public</span> <span class="type"><a href="class.pdostatement.html" class="type PDOStatement">PDOStatement</a></span> <span class="methodname"><strong>PDO::prepare</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$statement</code></span>
   [, <span class="methodparam"><span class="type">array</span> <code class="parameter">$driver_options</code><span class="initializer"> = array()</span></span>
  ] )</div>


  <p class="para rdfs-comment">
   Prepares an SQL statement to be executed by the
   <span class="function"><a href="pdostatement.execute.html" class="function">PDOStatement::execute()</a></span> method. The SQL statement can
   contain zero or more named (:name) or question mark (?) parameter markers
   for which real values will be substituted when the statement is executed.
   You cannot use both named and question mark parameter markers within the same
   SQL statement; pick one or the other parameter style.
   Use these parameters to bind any user-input, do not include the user-input
   directly in the query.
  </p>
  <p class="para">
   You must include a unique parameter marker for each value you wish to pass
   in to the statement when you call <span class="function"><a href="pdostatement.execute.html" class="function">PDOStatement::execute()</a></span>.
   You cannot use a named parameter marker of the same name twice in a prepared
   statement. You cannot bind multiple values to a single named parameter in,
   for example, the IN() clause of an SQL statement.
  </p>
  <p class="para">
   Calling <span class="function"><strong>PDO::prepare()</strong></span> and
   <span class="function"><a href="pdostatement.execute.html" class="function">PDOStatement::execute()</a></span> for statements that will be
   issued multiple times with different parameter values optimizes the
   performance of your application by allowing the driver to negotiate
   client and/or server side caching of the query plan and meta information,
   and helps to prevent SQL injection attacks by eliminating the need to
   manually quote the parameters.
  </p>
  <p class="para">
   PDO will emulate prepared statements/bound parameters for drivers that do
   not natively support them, and can also rewrite named or question mark
   style parameter markers to something more appropriate, if the driver
   supports one style but not the other.
  </p>
 </div>

 <div class="refsect1 parameters" id="refsect1-pdo.prepare-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<em><code class="parameter">statement</code></em></dt>

     <dd>

      <p class="para">
       This must be a valid SQL statement for the target database server.
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">driver_options</code></em></dt>

     <dd>

      <p class="para">
       This array holds one or more key=&gt;value pairs to set
       attribute values for the PDOStatement object that this method
       returns. You would most commonly use this to set the
       <em>PDO::ATTR_CURSOR</em> value to
       <em>PDO::CURSOR_SCROLL</em> to request a scrollable cursor.
       Some drivers have driver specific options that may be set at
       prepare-time.
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-pdo.prepare-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   If the database server successfully prepares the statement,
   <span class="function"><strong>PDO::prepare()</strong></span> returns a
   <a href="class.pdostatement.html" class="classname">PDOStatement</a> object.
   If the database server cannot successfully prepare the statement,
   <span class="function"><strong>PDO::prepare()</strong></span> returns <strong><code>FALSE</code></strong> or emits
   <a href="class.pdoexception.html" class="classname">PDOException</a> (depending on <a href="pdo.error-handling.html" class="link">error handling</a>).
  </p>
  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <p class="para">
    Emulated prepared statements does not communicate with the database server
    so <span class="function"><strong>PDO::prepare()</strong></span> does not check the statement.
   </p>
  </p></blockquote>
 </div>


 <div class="refsect1 examples" id="refsect1-pdo.prepare-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-900"><p><strong>Example #1 Prepare an SQL statement with named parameters</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">/*&nbsp;Execute&nbsp;a&nbsp;prepared&nbsp;statement&nbsp;by&nbsp;passing&nbsp;an&nbsp;array&nbsp;of&nbsp;values&nbsp;*/<br /></span><span style="color: #0000BB">$sql&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'SELECT&nbsp;name,&nbsp;colour,&nbsp;calories<br />&nbsp;&nbsp;&nbsp;&nbsp;FROM&nbsp;fruit<br />&nbsp;&nbsp;&nbsp;&nbsp;WHERE&nbsp;calories&nbsp;&lt;&nbsp;:calories&nbsp;AND&nbsp;colour&nbsp;=&nbsp;:colour'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$sth&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$dbh</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">prepare</span><span style="color: #007700">(</span><span style="color: #0000BB">$sql</span><span style="color: #007700">,&nbsp;array(</span><span style="color: #0000BB">PDO</span><span style="color: #007700">::</span><span style="color: #0000BB">ATTR_CURSOR&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">PDO</span><span style="color: #007700">::</span><span style="color: #0000BB">CURSOR_FWDONLY</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">$sth</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">execute</span><span style="color: #007700">(array(</span><span style="color: #DD0000">':calories'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">150</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">':colour'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'red'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">$red&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$sth</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">fetchAll</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">$sth</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">execute</span><span style="color: #007700">(array(</span><span style="color: #DD0000">':calories'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">175</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">':colour'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'yellow'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">$yellow&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$sth</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">fetchAll</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>
   <div class="example" id="example-901">
    <p><strong>Example #2 Prepare an SQL statement with question mark parameters</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">/*&nbsp;Execute&nbsp;a&nbsp;prepared&nbsp;statement&nbsp;by&nbsp;passing&nbsp;an&nbsp;array&nbsp;of&nbsp;values&nbsp;*/<br /></span><span style="color: #0000BB">$sth&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$dbh</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">prepare</span><span style="color: #007700">(</span><span style="color: #DD0000">'SELECT&nbsp;name,&nbsp;colour,&nbsp;calories<br />&nbsp;&nbsp;&nbsp;&nbsp;FROM&nbsp;fruit<br />&nbsp;&nbsp;&nbsp;&nbsp;WHERE&nbsp;calories&nbsp;&lt;&nbsp;?&nbsp;AND&nbsp;colour&nbsp;=&nbsp;?'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$sth</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">execute</span><span style="color: #007700">(array(</span><span style="color: #0000BB">150</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'red'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">$red&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$sth</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">fetchAll</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">$sth</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">execute</span><span style="color: #007700">(array(</span><span style="color: #0000BB">175</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'yellow'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">$yellow&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$sth</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">fetchAll</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-pdo.prepare-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="pdo.exec.html" class="function" rel="rdfs-seeAlso">PDO::exec()</a> - 执行一条 SQL 语句，并返回受影响的行数</span></li>
    <li class="member"><span class="function"><a href="pdo.query.html" class="function" rel="rdfs-seeAlso">PDO::query()</a> - Executes an SQL statement, returning a result set as a PDOStatement object</span></li>
    <li class="member"><span class="function"><a href="pdostatement.execute.html" class="function" rel="rdfs-seeAlso">PDOStatement::execute()</a> - 执行一条预处理语句</span></li>
   </ul>
  </p>
 </div>

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